JP4496489B2 - Method for controlling raw sludge supply amount of dehydrator and its control device - Google Patents

Description

  The present invention relates to a sludge tempering treatment before a dehydrator for adding a flocculant to water sludge, sewage sludge, industrial wastewater sludge, etc. In combination, the sludge pump and chemical injection pump are mutually managed, the raw sludge supply flow rate is kept constant, and the supply pressure of the coagulated sludge that is press-fitted into the dehydrator is adjusted within the specified value. The present invention relates to a method and a raw sludge supply amount control device.

  In big cities, sludge from many treatment plants is accepted and concentrated. Since the storage tank is small with respect to the amount of sludge received and a large amount of processing is required, continuous operation with a constant flow rate of the supplied raw sludge is required. In the constant control of sludge press-fitting pressure for stable operation of the dehydrator, the amount of solids processed varies due to variations in sludge concentration and filterability. The higher the sludge, the greater the amount of solids processed, and the lower the concentration, the lower the amount of solids processed. As a sludge coagulation treatment device installed in the previous stage of the conventional screw press, a line mixer and a coagulation mixing tank are connected in series to the sludge press-in pump, and the sludge and polymer coagulant are stirred by the supply pressure of the press-in pump. The aggregating apparatus to be mixed has been proposed by the applicant of the present invention as described in Patent Document 1, for example. In addition, the agglomeration mixing tank with a concentration function that can be concentrated is divided into an agglomeration part with a stirring blade in a closed processing tank and a concentrating part with a screen stretched, and the stock solution supply pump and the filtrate quantitative discharger are controlled. And the applicant of this invention has also proposed the sludge concentration apparatus which concentrates agglomerated sludge to a set magnification as it is described in patent document 2. FIG.

Japanese Patent Laid-Open No. 10-192900 (paragraph number 0007, FIG. 2) JP 2000-325997 A (paragraph numbers 0008 to 0010, FIG. 3)

  A constant flow rate operation that generates flocs of suspended solids in a conventional standard flocculation mixing tank and supplies a predetermined flow rate of flocculated sludge to the screw press can handle solids processing volume increases or sludge properties deteriorate. It was difficult. In order to perform a constant flow rate operation by the conventional method, it is necessary to select a screw press that is one step larger in order to allow a sufficient processing capacity of the screw press. The sludge agglomeration device, in which a line mixer and a coagulation mixing tank are connected in series between the sludge press-in pump and the pressure dehydrator, fully mixes the polymer flocculant with a single press-in pump, and is diluted. Mixing from sludge to highly viscous sludge is possible, but with constant control of the raw sludge supply amount of the dewatering machine that keeps the flow rate of the raw sludge supplied to the dehydrator constant, the sludge concentration and sludge properties of the raw sludge are adjusted. There is a fluctuation, and the moisture content of the dewatered cake may vary, which may hinder the subsequent process. In addition, the conventional coagulation mixing tank with a concentration function can obtain a predetermined concentrated sludge by regulating the discharge amount of the filtrate, but it is limited to the ability to cope with rapidly changing sludge concentration and sludge properties. There is. This invention, as a sludge conditioning device in front of the dehydrator, a coagulation mixing tank with a concentration function and a standard coagulation mixing tank are arranged in series, and a constant flow of raw sludge is supplied to the coagulation mixing tank with a concentration function, The rate of chemical flocculant added to the coagulation / mixing tank with concentration function as the tank pressure of the coagulation / mixing tank with concentration function changes as the pressure of the coagulation sludge injected into the dehydrator remains within the specified value. A control method and a control device for a constant amount of raw sludge supplied to a dehydrator for maintaining a tank internal pressure of a coagulation mixing tank with a concentration function within a specified value by adjusting

  The raw sludge supply amount constant control method of the dehydrator according to the present invention is a first-stage agglomeration mixing tank with a concentration function in which a quantitative sludge pump and a polymer supply pump are connected, and a concentrated sludge pump and a polymer supply pump are connected. In the sludge pretreatment device, a second stage coagulation mixing tank is arranged in series, and the coagulation sludge is pressed into the dehydrator by the tank pressure of the coagulation mixing tank. Concentrated sludge concentration is adjusted by supplying to a coagulation mixing tank with a concentration function, and concentrated sludge from which a part of the filtrate has been separated is pumped to the coagulation mixing tank and concentrated so that the tank internal pressure of the coagulation mixing tank is constant. After controlling the number of revolutions of the sludge pump to maintain the pressure of the coagulated sludge that is injected into the dehydrator, the high pressure supplied to the coagulation mixing tank with the concentration function according to the fluctuation of the tank internal pressure of the coagulation mixing tank with the concentration function With concentration function by changing the drug injection rate of molecular flocculant When the internal pressure of the collection tank is maintained within the specified value, and the sludge flow rate of the concentrated sludge cannot be improved within the specified value, a polymer flocculant is added to the coagulation mixing tank to improve the filterability of the coagulated sludge. This is a method to control the amount of raw sludge supplied to the dehydrator to be improved, supplying a constant flow of raw sludge, adjusting the concentration concentration in the first stage coagulation mixing tank with a concentration function, and treating the amount in the second stage coagulation mixing tank. By increasing or decreasing the pressure, the press-fitting pressure of the coagulated sludge that is press-fitted into the dehydrator can be maintained within a specified value.

  And the constant sludge supply amount control method of the dehydrator for fluctuation of sludge concentration is the concentrated sludge pump when the sludge concentration of the raw sludge becomes low, the solids processing amount decreases and the tank internal pressure of the coagulation mixing tank decreases. After increasing the rotation speed of the coagulation sludge and keeping the pressure of the coagulated sludge injected into the dehydrator within the specified value, the amount of the polymer coagulant added to the coagulation mixing tank with the concentration function is reduced to increase the concentration rate. Decrease, increase dehydrator load and increase tank pressure of coagulation mixing tank, return the sludge amount of the concentrated sludge to the set value, increase the sludge concentration of the raw sludge, increase the solids treatment amount When the tank internal pressure of the flocculation / mixing tank rises, the rotational speed of the concentrated sludge pump is lowered to maintain the pressure of the flocculated sludge to be pressed into the dehydrator within the specified value, Concentrate by adding more polymer flocculant to be added To reduce the load on the dehydrator, lower the tank pressure of the coagulation mixing tank, return the sludge amount of the concentrated sludge to the set value, and supply the raw sludge at a constant flow rate to the coagulation mixing tank with a compression function. On the other hand, this is a method for controlling the amount of raw sludge to be supplied to the dehydrator to maintain the supply pressure of the coagulated sludge that is press-fitted into the dehydrator within a specified value.

  Furthermore, when the sludge amount of the concentrated sludge to be pumped to the flocculation mixing tank does not decrease within the specified value continuously for a predetermined time even if the addition amount of the polymer flocculant added to the flocculation mixing tank with a concentration function is reduced, Decrease the filterability of the coagulated sludge supplied to the dehydrator by reducing the polymer coagulant added to the coagulation mixing tank, and raise the tank pressure of the coagulation mixing tank to return the sludge amount of the concentrated sludge to the set value. At the same time, if the amount of sludge in the concentrated sludge does not increase within the specified value continuously for a predetermined time even if the amount of the polymer flocculant added is increased, the polymer flocculant added to the flocculent mixing tank is increased and dewatered. This is a method for controlling the amount of raw sludge supplied to the dehydrator to improve the filterability of the coagulated sludge injected into the machine and lower the tank pressure in the coagulation mixing tank to return the sludge amount of the concentrated sludge to the set value.

  The constant sludge supply control method of the dehydrator for fluctuations in sludge properties improves the sludge properties of the raw sludge, reduces the tank internal pressure of the coagulation mixing tank, and increases the amount of concentrated sludge pumped to the coagulation mixing tank. When the slag is concentrated, the amount of the polymer flocculant added to the flocculation / mixing tank with a concentration function is reduced to reduce the concentration rate, the load on the dehydrator is increased to increase the tank pressure of the flocculation / mixing tank, and the concentrated sludge When the sludge amount of the raw sludge deteriorates and the internal pressure of the coagulation mixing tank increases and the amount of concentrated sludge pumped to the coagulation mixing tank decreases, the concentration function is The polymer flocculant added to the coagulation mixing tank is increased to improve the concentration rate, the load on the dehydrator is reduced, the tank pressure of the coagulation mixing tank is lowered, and the sludge amount of the concentrated sludge is returned to the set value. This is a method for controlling the amount of raw sludge supplied to the dehydrator.

  And even if the sludge properties of the raw sludge deteriorates and the amount of the polymer flocculant added to the coagulation mixing tank with a concentration function is increased, the sludge amount of the concentrated sludge does not return to the specified value continuously for a predetermined time, The polymer flocculant is added to the coagulation mixing tank to improve the filterability, the coagulation sludge supplied to the dehydrator is increased, the tank internal pressure of the coagulation mixing tank is decreased, and the sludge amount of the concentrated sludge falls within the specified value. This is a method for controlling the amount of raw sludge supplied to the dehydrator to be restored.

  The raw sludge supply amount constant control device for carrying out the dewatering device raw sludge supply amount constant control method according to the present invention is a sludge pretreatment device provided at the front stage of the dehydrator, in the first stage coagulation mixing tank with a concentration function. A fixed-quantity sludge pump and a polymer feed pump are connected to the tank, and a constant flow of raw sludge and a polymer flocculant are supplied to the coagulation mixing tank with a concentration function, and the filtrate is separated from the sludge that has generated floc. Concentration sludge pump and polymer supply pump are connected to the second stage flocculation and mixing tank to extract the concentrated sludge from the flocculation and mixing tank with concentration function, and the filterability and the amount of flocculated sludge extracted in the flocculation and mixing tank. This is a device for controlling the amount of raw sludge supplied to the dehydrator to maintain the press-fitting pressure of the coagulated sludge that is injected into the dehydrator. , Mutual pipe of sludge pump and chemical injection pump Accordingly, it is possible to a constant flow rate of the raw sludge to be supplied to the dehydrator.

  A specific control device for the raw sludge supply amount of the dehydrator controls the rotation speed of the concentrated sludge pump by receiving the pressure sensor for detecting the tank internal pressure of the second stage coagulation mixing tank and the detection signal of the pressure sensor. A pressure flow controller is installed to adjust the sludge flow rate of the concentrated sludge to be pumped to the flocculation mixing tank so that the tank internal pressure of the flocculation mixing tank is kept constant and the tank internal pressure of the flocculation mixing tank with the first concentration function is maintained. A pressure sensor that detects the pressure, a flow rate controller that receives the detection signal of the pressure sensor to increase or decrease the rotation speed of the polymer supply pump, and a command signal for increasing or decreasing the rotation speed to receive the rotation speed of the polymer supply pump A solid proportional injection controller to be controlled is installed to supply raw sludge at a constant flow rate to the coagulation mixing tank with a concentration function, and while maintaining the press-fitting pressure of the coagulated sludge to be injected into the dehydrator within the specified value, concentration is performed. Inside the tank of a functional coagulation mixing tank The amount of polymer flocculant added to the coagulation / mixing tank with concentration function is adjusted to keep the tank internal pressure of the coagulation / mixing tank with concentration function within the specified value. It is a control device, and the concentration of concentrated sludge can be adjusted in a coagulation mixing tank with a concentration function, and the amount of solid matter can be adjusted in the coagulation mixing tank before being put into a dehydrator.

  Furthermore, when only the polymer flocculant added to the flocculation / mixing tank with a concentration function is insufficient to improve the flocculation, and the sludge flow rate of the concentrated sludge cannot be improved within the specified value, the sludge flowmeter detects the sludge flow rate of the concentrated sludge. And a flow rate controller that receives a detection signal of the detected sludge flow rate, and a polymer coagulant is added to the coagulation mixing tank to improve the coagulation state of the coagulated sludge supplied to the dehydrator. This is a constant sludge supply amount control device.

  The method for controlling the amount of raw sludge supplied to a dehydrator according to the present invention and the control device thereof are provided with a coagulation mixing tank with a concentration function in the previous stage of a standard coagulation mixing tank, and the concentration of concentrated sludge in the coagulation mixing tank with a concentration function. The amount of solids processed is adjusted in the coagulation / mixing tank before being put into the dehydrator, so that the margin of the dehydrator is reduced and a small dehydrator can be employed. For fluctuations in the raw sludge concentration, the tank internal pressure of the coagulation mixing tank with concentration function and the tank internal pressure of the coagulation mixing tank are detected, and the tank internal pressure of the coagulation mixing tank is kept constant, while the coagulation mixing tank with the first concentration function By adjusting the amount of the polymer flocculant added to improve the concentration rate and improve the dewaterability, the load on the dehydrator can be equalized. And even if there are fluctuations in the solid matter throughput of the raw sludge, it is possible to perform a constant flow rate operation of the dehydrator that maintains the coagulated sludge supplied to the dehydrator within the reference value. In addition, for the deterioration of sludge properties, the tank internal pressure of the flocculation mixing tank with concentration function is detected and the concentration rate of the flocculation mixing tank with concentration function in the first stage is improved. This makes it possible to control the supply of raw sludge at a constant rate. If necessary, increasing the amount of polymer flocculant added to the second flocculation / mixing tank will improve flocculation, improve the filterability of the flocculated sludge, and equalize the dewaterer throughput and water content. it can.

  The raw sludge supply amount constant control method and the raw sludge supply amount control device of the dehydrator according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a flocculation process flow for the constant sludge supply amount control of the dehydrator. The sludge supply pipe 2 connected to the sludge storage tank 1 is connected to the tank bottom of the closed coagulation mixing tank 3 with a concentration function, and the sludge storage is performed by the fixed-quantity sludge pump SP1 disposed in the sludge supply pipe 2. The raw sludge Q1 having a constant flow rate is always supplied from the tank 1 to the coagulation mixing tank 3 with a concentration function. A line mixer 4 is disposed in the sludge supply pipe 2 behind the fixed-quantity sludge pump SP1, and the inorganic flocculant R is added to the raw sludge Q1 from the branch pipe 5 connected to the sludge supply pipe 2, and the line mixer 4 Stir and mix to coagulate the metal salt. A chemical solution supply pipe 7 is connected to a polymer dissolution tank 6 that stores the polymer flocculant, and the chemical solution supply pipe 7 is connected to the sludge supply pipe 2 behind the line mixer 4. The chemical solution supply pipe 7 is provided with a polymer supply pump PP1 for increasing or decreasing the amount of the polymer flocculant P1 added. The polymer supply pump PP1 is mixed with the inorganic flocculant R and mixed with the raw sludge Q1 having a constant flow rate. The molecular flocculant P1 is added and supplied to the flocculent mixing tank 3 with a concentration function.

  FIG. 2 is a longitudinal sectional view of the coagulation / mixing tank with concentration function, in which a drive unit 8 is disposed on the top wall of the coagulation / mixing tank 3 with concentration function, and a stirrer 9 is connected to the drive unit 8. The rotating shaft 10 of the stirrer 9 hangs down on the lower half of the aggregating and mixing tank 3 with a concentration function, and the stirring blade 11 is fixed to the lower end of the rotating shaft 10. This stirring blade 11 is attached to the upper and lower two stages with a phase shifted by 45 °, and a baffle plate 12 is disposed on the peripheral wall of the lower part of the coagulation mixing tank 3 with a concentration function so as to face the stirring blade 11. A screen 13 is stretched on the peripheral wall of the upper half of the agglomeration mixing tank 3 with a concentrating function, and a filtrate chamber 14 is formed in the peripheral part. A scraper 15 fixed to the rotary shaft 10 is slidably contacted with the screen 13. is there. A disc-shaped partition plate 16 having a peripheral portion opened to the lower end of the scraper 15 is fixed, and the lower half of the coagulation mixing tank 3 with a concentration function is the aggregation portion A and the upper half is the concentration portion B. . The raw sludge Q1 mixed with the inorganic flocculant R flowing in from the inflow pipe 17 at the bottom of the flocculent admixing tank 3 with the concentration function and the polymer flocculant P1 are stirred and mixed by the stirrer 9 to generate a floc of suspended substances. . The sludge that has generated the flocculated flocs in the flocculating part A is transferred to the upper concentrating part B and concentrated while separating the filtrate S on the screen 13. The filtrate S that has flowed into the filtrate chamber 14 is discharged from the filtrate extraction pipe 18, and the concentrated sludge Q 2 that is separated and concentrated by part of the filtrate S is extracted from the concentrated sludge extraction pipe 19.

  As shown in FIG. 1, a standard flocculation / mixing tank 21 of the second stage in which the pressure feed pipe 20 connected to the concentrated sludge extraction pipe 19 for extracting the concentrated sludge Q2 of the flocculation / mixing tank 3 with the concentration function of the first stage is sealed. The concentrated sludge Q2 is press-fitted into the flocculation and mixing tank 21 by the concentrated sludge pump SP2 disposed in the pressure feed pipe 20. A chemical solution branch pipe 7a is connected to the chemical solution supply pipe 7 in the preceding stage of the polymer supply pump PP1 that supplies the polymer coagulant P1 to the coagulation mixing tank 3 with a concentration function. The rear end of the branched chemical solution branch pipe 7a is connected to the pressure feed pipe 20 behind the concentrated sludge pump SP2, and a polymer supply pump PP2 for transferring the polymer flocculant P2 is disposed in the chemical solution branch pipe 7a. is there. The polymer flocculant P2 is added to the concentrated sludge Q2 extracted by the concentrated sludge pump SP2 from the coagulation-mixing tank 3 with a concentration function, if necessary, and pumped to the coagulation-mixing tank 21 and stirred in the coagulation-mixing tank 21. Stir and mix in machine 22 to produce a strong cohesive floc. A press-fit pipe 23 for extracting the coagulated sludge Q3 is connected to the coagulation-mixing tank 21, and a screw press 24 is disposed at the rear end of the press-fit pipe 23. The supply of the coagulated sludge Q3 to the screw press 24 is performed by solid-liquid separation by press-fitting from the press-in pipe 23 with the tank internal pressure of the closed coagulation mixing tank 21. In the embodiment of the present invention, a screw press is illustrated as a dehydrator. However, a centrifugal dehydrator, a belt press, or a filter press may be used.

  As shown in FIG. 1, a pressure sensor PS2 is provided in the second stage agglomeration mixing tank 21, and the internal pressure of the agglomeration mixing tank 21 that pumps the concentrated sludge Q2 is detected. A pressure flow controller 25 for receiving the detected detection signal of the pressure sensor PS2 is disposed, and a reference value for the tank internal pressure of the coagulation mixing tank 21 is set in the pressure flow controller 25 in advance. Although the solid matter throughput of the raw sludge Q1 fluctuates due to changes in sludge concentration and filterability, the screw press 24 requires stable operation, and the pressure flow controller 25 outputs a pressure detection signal detected by the pressure sensor PS2. Receiving and adjusting the rotation speed of concentrated sludge pump SP2 so that the tank internal pressure of coagulation mixing tank 21 may be maintained constant.

  As shown in FIG. 1, a pressure sensor PS1 is disposed in the concentrating part B for separating a part of the filtrate in the first-stage condensing and mixing tank 3 with a concentrating function, and detects the tank internal pressure of the concentrating part B. Due to changes in sludge properties and raw sludge concentration, the amount of concentrated sludge Q2 withdrawn from the concentration section B of the coagulation mixing tank 3 with concentration function varies, and the tank internal pressure of the coagulation mixing tank 3 with concentration function changes. At the same time, by adjusting the rotation speed of the concentrated sludge pump SP2, the sludge amount of the concentrated sludge Q2 withdrawn from the coagulation mixing tank 3 with the concentration function varies, and the tank internal pressure of the coagulation mixing tank 3 with the concentration function changes. A flow rate controller 26 for receiving a detection signal for detecting the tank internal pressure of the coagulation mixing tank 3 with the concentration function by the pressure sensor PS1 is provided. The flow rate controller 26 is set in advance with a reference value for the tank internal pressure of the coagulation mixing tank 3 with a concentration function. When the solids proportional injection controller 27 is connected to the flow rate controller 26 and the tank internal pressure of the coagulation mixing tank 3 with the concentration function falls outside the range of the reference value, the flow rate controller 26 controls the polymer supply pump PP1. A command signal for increasing / decreasing the number of revolutions is transmitted to increase / decrease the amount of addition from the reference value of the polymer flocculant P1. Concentration meter D and sludge flow meter F1 are installed in sludge supply pipe 2 that always draws raw sludge Q1 with a constant flow rate from sludge storage tank 1, and the detection signal of sludge concentration and sludge flow rate of raw sludge Q1 is solid. It is transmitted to the physical proportional injection controller 27, the amount of the polymer flocculant P1 added to the amount of the solid matter treated in the raw sludge Q1 is calculated, and the reference value of the polymer flocculant P1 is set in advance. In the embodiment of the present invention, the tank internal pressure of the coagulation mixing tank 3 with the concentration function is detected by the pressure sensor PS1 every minute, and the detection signal is transmitted to the flow rate controller 26.

  The flow controller 26 compares the transmitted detection signal of the pressure of the concentrated sludge Q2 with a reference value, and when it is out of the set range, commands to increase or decrease the addition rate of the polymer flocculant P1 are controlled in proportion to the solid matter. To the device 27. Based on the command signal of the flow controller 26, the solid proportional injection controller 27 controls the rotation speed of the polymer supply pump PP1. In the embodiment of the present invention, the tank internal pressure of the coagulation mixing tank 3 with the concentration function with respect to the reference value 0.5 to 1.0% of the addition amount of the polymer flocculant P1 is continuously 5 kPa for one minute of the set time. When the value is higher, the rotation speed of the polymer supply pump PP1 is adjusted so that the amount of the polymer flocculant P1 added is increased by 0.01 point. The reason why the tank internal pressure of the flocculation / mixing tank 3 with the concentration function increases is expected to be an increase in the concentration of the raw solution of the raw sludge Q1 and a deterioration in the filterability. The filterability of the raw sludge Q1 is improved, the concentration rate of the coagulation mixing tank 3 with a concentration function is increased, and the sludge amount of the concentrated sludge Q2 is reduced. On the contrary, when the pressure with respect to the reference value of 0.5 to 1.0% of the addition amount of the polymer flocculant P1 is 5 kPa or more continuously for 1 minute, the polymer flocculant P1 is decreased by 0.01 point. The rotation speed of the polymer supply pump PP1 is adjusted. The reason why the tank internal pressure of the flocculation / mixing tank 3 with a concentration function is low is expected to be a decrease in the concentration of the stock solution and an improvement in filterability.

  A polymer supply for adding a sludge flowmeter F3 to the pressure feed pipe 20 near the back of the concentrated sludge pump SP2 for extracting the concentrated sludge Q2 from the coagulation mixing tank 3 with a concentration function and a polymer flocculant to the coagulation mixing tank 3 with a concentration function. A chemical flow meter F4 is disposed in the chemical branch pipe 7a near the rear of the pump PP2. The sludge flow rate of the concentrated sludge Q2 extracted from the coagulation mixing tank 3 with a concentration function is detected by the sludge flow meter F3, and the detection signal is transmitted to the flow rate controller 28. When the amount of sludge of the concentrated sludge Q2 withdrawn from the coagulation / mixing tank 3 with the concentration function does not return to the set flow rate for more than 5 minutes continuously only by increasing / decreasing the polymer flocculant P1 added to the coagulation / mixing tank 3 with the concentration function. The flow controller 28 increases or decreases the rotational speed of the polymer supply pump PP2 for adding the polymer flocculant P2 to the flocculation mixing tank 21. If the sludge amount of the concentrated sludge Q2 does not increase within the specified value, the amount of the polymer flocculant P2 pumped to the flocculation mixing tank 21 is increased to improve the flocculation state in the flocculation mixing tank 21. Moreover, if the sludge amount of the concentrated sludge Q2 does not fall within a specified value, the polymer flocculant P2 added to the flocculation mixing tank 21 is reduced, and the filterability of the flocculated sludge Q3 supplied to the screw press 24 is lowered.

FIG. 3 is a block diagram of the control of the constant amount of raw sludge supplied to the dehydrator. The concentrated sludge pump SP2 for pumping the concentrated sludge Q2 is configured so that the pressure sensor PS2 for detecting the tank internal pressure of the coagulation mixing tank 21 becomes the set pressure. In addition, the operation of changing the sludge flow rate is performed. By adjusting the sludge flow rate of the concentrated sludge Q2 by the concentrated sludge pump SP2 and changing the properties and concentration of the raw sludge, the sludge flow rate of the concentrated sludge Q2 that is concentrated and extracted in the coagulation mixing tank 3 with a concentration function varies. In order to control the amount of raw sludge supplied to the dehydrator,
(1) Start the operation of the screw press 24,
(2) The tank internal pressure of the second stage coagulation mixing tank 21 into which the coagulated sludge Q3 is press-fitted into the screw press 24 is detected by the pressure sensor PS2, and is compared with the specified value of the reference pressure by the pressure flow controller 25.
(3) When the tank internal pressure of the flocculation / mixing tank 21 becomes higher than the specified value, the concentrated sludge Q2 extracted from the flocculation / mixing tank 3 with the concentration function in the first stage decreases.
(4) When the pressure sensor PS1 that detects the tank internal pressure of the flocculation mixing tank 3 with the concentration function continuously rises by more than 5 kPa from the upper limit of the specified value in one minute of the set time,
(5) The polymer flocculant P1 supplied to the coagulation / mixing tank 3 with the concentration function is increased by 0.01 point from the specified value, the filterability is improved, and the amount of filtrate S discharged from the coagulation / mixing tank 3 with the concentration function is increased. And reduce the tank internal pressure of the coagulation mixing tank 3 with a concentration function.
vice versa,
(2) The tank internal pressure of the agglomeration mixing tank 21 is detected by the pressure sensor PS2, and the tank internal pressure is compared with a specified value by the pressure flow controller 25.
(6) When the tank internal pressure of the coagulation mixing tank 21 becomes lower than the specified value, the concentrated sludge Q2 extracted from the coagulation mixing tank 3 with the concentration function increases.
(7) When the pressure sensor PS1 that detects the tank internal pressure of the flocculation / mixing tank 3 with the concentration function is continuously lowered for 5 minutes from the lower limit of the specified value for 1 minute of the set time,
(8) Decrease the polymer flocculant P1 to be added to the coagulation / mixing tank 3 with the concentration function by 0.01 point from the specified value, reduce the amount of filtrate S discharged from the coagulation / mixing tank 3 with the concentration function, and coagulate with the concentration function. The tank internal pressure of the mixing tank 3 is increased.

When the sludge flow rate of the concentrated sludge Q2 does not return to the standard set value for 5 minutes or more continuously, the flow rate controller 28 rotates the rotation speed of the polymer supply pump PP2 that adds the polymer flocculant P2 to the flocculation mixing tank 21. Increase or decrease.
(9) By simply increasing or decreasing the polymer flocculant P1 added to the coagulation / mixing tank 3 with the concentration function, the sludge flow rate of the concentrated sludge Q2 extracted from the coagulation / mixing tank 3 with the concentration function is continuously defined for 5 minutes. If you do not recover from the upper limit of the value,
(10) The polymer flocculant P2 is added to the concentrated sludge Q2 that is press-fitted into the flocculation / mixing tank 21 with a decrease of 0.01 points from the specified value.
(11) If the sludge amount of the concentrated sludge Q2 withdrawn from the coagulation mixing tank 3 with the concentration function does not return from the lower limit of the specified value continuously for 5 minutes of the set time,
(12) The polymer flocculant P2 is added to the concentrated sludge Q2 that is press-fitted into the flocculation mixing tank 21 with an increase of 0.01 points from the specified value.
The above operation is repeated, and the raw sludge Q1 having a constant flow rate is always supplied from the sludge storage tank 1 to the coagulation mixing tank 3 with the concentration function, and the aggregation state of the coagulation mixing tank 3 with the concentration function and the coagulation mixing tank 21 is adjusted and concentrated. Control which harmonizes the flow rate balance of sludge Q2 and filtrate S is performed.

Based on the flowchart of FIG. 1, the coagulation mixing tank 3 with a concentration function in which the quantitative sludge pump SP1 and the polymer supply pump PP1 are connected in the first stage, and the extraction sludge conditioning apparatus in the second stage is connected to the sludge conditioning apparatus in the first stage. A coagulation mixing tank 21 in which the concentrated sludge pump SP2 and the polymer supply pump PP2 are connected is arranged in series to adjust the phenomenon of changes in the sludge concentration and sludge properties of the raw sludge Q1 and the amount of addition of the polymer flocculant. We considered measures. The first stage coagulation-mixing tank 3 with a concentration function is operated at a constant flow rate by the quantitative sludge pump SP1, and the second stage coagulation-mixing tank 21 is controlled by a screw press 24 as a constant press-fitting pressure control of the coagulation sludge Q3 to the screw press 24. Prioritized stable operation. The concentrated sludge pump SP2 is controlled to change the flow rate of the concentrated sludge Q2 so that the pressure sensor PS2 for detecting the tank internal pressure of the flocculation mixing tank 21 is constant. And although the chemical injection rate of the polymer flocculant P1 to the flocculation / mixing tank 3 with the concentration function is set to a specified value, if the concentration becomes worse due to fluctuations in the sludge properties, There is a concern about clogging of the screen 13. The tank internal pressure of the coagulation mixing tank 3 with the concentration function is detected by the pressure sensor PS1, and when the tank internal pressure is equal to or higher than the upper limit of the specified value, the chemical injection rate of the polymer coagulant P1 in the coagulation mixing tank 3 with the concentration function is It was decided to increase the injection rate to “0.01 points”. If the sludge flow rate of the concentrated sludge Q2 cannot be improved within the specified range even if the chemical injection rate of the polymer flocculant P1 in the flocculation / mixing tank 3 with the concentration function is changed, the polymer flocculation to be added to the flocculation / mixing tank 21 The chemical injection rate of the agent P2 was increased to “set chemical injection rate + 0.01 points”.
Table 1 shows the amount of polymer flocculants P1 and P2 added as a countermeasure against the phenomenon of tank internal pressure, filtrate amount, sludge concentration in the coagulation mixing tank 3 with a concentration function and tank internal pressure in the standard coagulation mixing tank 21. Increase or decrease.

(1) Phenomenon when the concentration of raw sludge Q1 is reduced: Since the amount of solids processed is reduced, the tank internal pressure of the second stage agglomeration mixing tank 21 is reduced. The sludge flow rate of the concentrated sludge Q2 withdrawn from the first-stage flocculation / mixing tank 3 with the concentration function increases, and the discharge amount of the filtrate S discharged from the flocculation / mixing tank 3 with the concentration function naturally decreases. It is necessary to reduce the supply amount of the concentrated sludge Q2 to be pumped to the flocculation / mixing tank 21.
Operation 1: The amount of the polymer flocculant P1 added to the flocculation / mixing tank 3 with the concentration function is decreased, and the sludge amount of the concentrated sludge Q2 is decreased by deteriorating the filterability.
Operation 2: If the amount of the sludge of the concentrated sludge Q2 does not decrease within the specified amount only by reducing the polymer flocculant P1 added to the coagulation / mixing tank 3 with the concentration function, it is supplied to the coagulation / mixing tank 21. The amount of the polymer flocculant P2 is reduced to adjust the aggregation state in the aggregation mixing tank 21. If the filterability of the coagulated sludge Q3 supplied to the screw press 24 is lowered, the tank internal pressure of the coagulation mixing tank 21 can be increased.

(2) Phenomenon when the concentration of raw sludge Q1 increases: Since the amount of solids processing increases, the load on the screw press 24 increases, the tank internal pressure of the second flocculation mixing tank 21 increases, and the flocculation mixing The amount of concentrated sludge Q2 flowing into the tank 21 decreases. Since the sludge amount of the concentrated sludge Q2 discharged from the first stage flocculation / mixing tank 3 with the concentration function decreases, the tank internal pressure PS1 of the flocculation / mixing tank 3 with the concentration function increases. It is necessary to increase the filtrate S to be separated from the flocculation / mixing tank 3 with a concentration function and increase the concentration ratio.
Operation 1: Increasing the amount of the polymer flocculant P1 to be added to the coagulation / mixing tank 3 with the concentration function improves the sludge amount of the concentrated sludge Q2 discharged from the coagulation / mixing tank 3 with the concentration function, and the tank internal pressure of the coagulation / mixing tank 21 Decreases, and the concentrated sludge Q2 can be increased.
Operation 2: If the amount of the sludge of the concentrated sludge Q2 does not increase within the specified value only by the addition amount of the polymer flocculant P1 added to the first stage agglomeration mixing tank 3 with the concentration function, the second stage If the polymer flocculant P2 added to the coagulation mixing tank 21 is increased to improve the filterability of the coagulated sludge Q3 supplied to the screw press 24, the amount of sludge of the concentrated sludge Q2 increases and the treatment amount becomes the specified value. Return inside.

(3) Phenomenon when the filterability of the raw sludge Q1 is improved: The tank internal pressure of the second flocculation / mixing tank 21 decreases, and the concentrated sludge Q2 flowing into the flocculation / mixing tank 21 increases. The filtrate S that naturally separates from the first stage flocculation / mixing tank 3 with the concentration function decreases, and the concentration rate in the flocculation / mixing tank 3 with the concentration function decreases.
The operation | movement which suppressed the concentration magnification of the coagulation sludge Q3 supplied to the screw press 24 is needed.
Operation 1: If the polymer flocculant P1 added to the flocculation / mixing tank 3 with the concentration function is decreased, the concentration rate of the concentrated sludge Q2 extracted from the flocculation / mixing tank 3 with the concentration function decreases, and the tank of the flocculation / mixing tank 21 The internal pressure can be raised within a specified value.
Operation 2: Still, if the amount of the sludge of the concentrated sludge Q2 does not decrease within the specified value only by reducing the polymer flocculant P1 added to the coagulation / mixing tank 3 with the concentration function, it is supplied to the coagulation / mixing tank 21. The amount of the polymer flocculant P2 is reduced to adjust the aggregation state in the aggregation mixing tank 21. If the filterability of the coagulated sludge Q3 supplied to the screw press 24 is lowered, the tank internal pressure of the coagulation mixing tank 21 can be increased. The concentration rate of the coagulated sludge Q3 supplied to the screw press 24 is reduced to a predetermined press-fitting pressure.

(4) Phenomenon when the filterability of the raw sludge Q1 is deteriorated: The tank internal pressure of the second flocculation mixing tank 21 increases, and the amount of the sludge of the concentrated sludge Q2 flowing into the flocculation mixing tank 21 decreases.
Operation 1: The polymer flocculant P1 added to the coagulation mixing tank 3 with a concentration function is increased, and the concentration rate of the coagulation mixing tank 3 with a concentration function is increased. The concentrated sludge Q2 discharged from the flocculation / mixing tank 3 with the concentration function is improved, the tank internal pressure of the flocculation / mixing tank 21 is lowered, and the amount of sludge in the concentrated sludge Q2 can be increased.
Operation 2: Still further, when only the polymer flocculant P1 added to the flocculation / mixing tank 3 with the concentration function is insufficient in flocculation improvement and the amount of sludge of the concentrated sludge Q2 does not return to the specified value, the flocculation / mixing tank 21 If the filterability of the coagulated sludge Q3 supplied to the screw press 24 is improved by adding the polymer coagulant P2 to the tank, the tank internal pressure of the coagulation mixing tank 21 can be reduced to a specified value and the concentrated sludge Q2 can be increased. it can. If the coagulated sludge Q3 supplied to the screw press 24 is maintained at a constant press-fitting pressure, stable solid-liquid separation can be performed.

  A method for controlling the amount of raw sludge supplied to a dehydrator according to the present invention and a control device thereof are provided by arranging a coagulation mixing tank with a concentration function and a standard coagulation mixing tank in series, and coagulating the raw sludge having a constant flow rate with a concentration function. The polymer flocculant to be added to the coagulation mixing tank with concentration function as the internal pressure of the coagulation mixing tank with concentration function fluctuates while keeping the pressure of the coagulation sludge supplied to the mixing tank and pressed into the dehydrator constant. The sludge concentration is adjusted by changing the chemical injection rate, and the amount of solid matter is adjusted with a constant press-fitting pressure in the coagulation mixing tank before being put into the dehydrator. Amount of treatment and moisture content can be equalized. In other words, even if the raw sludge concentration changes and sludge properties deteriorate, the amount of processing can be kept constant to reduce the load on the subsequent stage and the load on the dehydrator can be equalized. A constant supply amount operation is possible, and an appropriate dehydrator with a reduced margin of the dehydrator can be employed. Therefore, it is suitable for a sludge refining device in front of a dehydrator such as a screw press, a centrifuge, a belt press, or a filter press.

FIG. 1 is a flow chart of a flocculation processing apparatus for constant control of raw sludge supply amount of a dehydrator according to the present invention. It is a longitudinal cross-sectional view of the coagulation mixing tank with a concentration function which concerns on this invention. Similarly, it is a block diagram of the raw sludge supply amount constant control of the dehydrator.

Explanation of symbols

3 Coagulation Mixing Tank 21 with Concentration Function Coagulation Mixing Tank 25 Pressure Flow Controller 24 Screw Press 26, 28 Flow Controller 27 Solid Proportion Injection Controller F3 Sludge Flowmeter P1, P2 Polymer Coagulant PP1, PP2 Polymer Supply Pump PS1, PS2 Pressure sensor Q1 Raw sludge Q2 Concentrated sludge Q3 Aggregated sludge SP1 Quantitative sludge pump SP2 Concentrated sludge pump S Filtrate

Claims (8)

  A first-stage coagulation mixing tank (3) with a concentrating function in which a quantitative sludge pump (SP1) and a polymer supply pump (PP1) are connected, and a second in which a concentrated sludge pump (SP2) and a polymer supply pump (PP2) are connected. In the sludge pretreatment device in which the flocculation / mixing tank (21) is arranged in series and the flocculated sludge (Q3) is pressed into the dehydrator (24) by the tank pressure of the flocculation / mixing tank (21). Concentrated sludge from which raw sludge (Q1) and a predetermined amount of polymer flocculant (P1) are supplied to the coagulation mixing tank with concentration function (3) to adjust the concentration of concentrated sludge and to separate a part of the filtrate (S) (Q2) is pumped to the flocculation / mixing tank (21), and the rotational speed of the concentrated sludge pump (SP2) is controlled so that the tank internal pressure of the flocculation / mixing tank (21) becomes constant, and the dehydrator (24). After maintaining the press-fitting pressure of the coagulated sludge (Q3) that is press-fitted into the coagulation, the coagulation with concentration function The flocculent mixing tank with concentration function (3) is changed by changing the chemical injection rate of the polymer flocculant (P1) to be supplied to the agglomeration mixing tank with concentration function (3) according to the fluctuation of the tank internal pressure of the Japanese tank (3). When the sludge amount of the concentrated sludge (Q2) cannot be improved within the specified value, the polymer flocculant (P2) is added to the coagulation mixing tank (21), A method for controlling the amount of raw sludge to be supplied to a dehydrator, characterized by improving the filterability of the coagulated sludge (Q3).   When the sludge concentration of the raw sludge (Q1) decreases, the solids processing amount decreases, and the tank internal pressure of the flocculation mixing tank (21) decreases, the rotational speed of the concentrated sludge pump (SP2) is increased and dewatered. After maintaining the press-fitting pressure of the coagulated sludge (Q3) injected into the machine (24) within the specified value, the amount of the polymer coagulant (P1) added to the coagulation mixing tank with concentration function (3) is reduced. The concentration rate is decreased, the load on the dehydrator (24) is increased, the tank pressure of the coagulation mixing tank (21) is increased, the sludge amount of the concentrated sludge (Q2) is returned to the set value, and the raw sludge ( When the sludge concentration in Q1) increases, the solids throughput increases, and the tank internal pressure in the flocculation mixing tank (21) rises, the rotational speed of the concentrated sludge pump (SP2) is lowered and the dehydrator (24) The press-fitting pressure of the coagulated sludge (Q3) that is press-fitted into the tank was maintained within the specified value. The concentration of the polymer flocculant (P1) added to the coagulation / mixing tank (3) with a concentration function is increased to improve the concentration rate, and the load on the dehydrator (24) is reduced to reduce the tank pressure of the coagulation / mixing tank (21). Is lowered, the sludge amount of the concentrated sludge (Q2) is returned to the set value, and the raw sludge (Q1) with a constant flow rate is supplied to the coagulation mixing tank (3) with a contraction function, while being supplied to the dehydrator (24). The method for controlling the amount of raw sludge to be supplied to a dehydrator according to claim 1, wherein the supply pressure of the coagulated sludge (Q3) to be injected is maintained within a specified value.   Even if the amount of the polymer flocculant (P1) added to the flocculation / mixing tank with concentration function (3) is reduced, the amount of sludge in the concentrated sludge (Q2) fed to the flocculation / mixing tank (21) continues for a predetermined time. When it does not decrease within the specified value, the polymer flocculant (P2) added to the flocculation mixing tank (21) is reduced to reduce the filterability of the flocculated sludge (Q3) supplied to the dehydrator (24), Even if the sludge amount of the concentrated sludge (Q2) is returned to the set value by increasing the tank pressure of the coagulation mixing tank (21), the concentrated sludge (Q2) is increased even if the addition amount of the polymer flocculant (P1) is increased. When the sludge amount of) does not increase within the specified value continuously for a predetermined time, the amount of the polymer flocculant (P2) added to the flocculation mixing tank (21) is increased, and the flocculated sludge (P) is press-fitted into the dehydrator (24). The filterability of Q3) is improved and the tank pressure of the coagulation mixing tank (21) is reduced. Raw sludge supply amount constant control method of the dehydrator according to claim 2, characterized in that to return to the set value sludge amount of concentrated sludge (Q2) Te.   When the sludge properties of the raw sludge (Q1) improve, the tank internal pressure of the flocculation / mixing tank (21) decreases and the amount of sludge in the concentrated sludge (Q2) pumped to the flocculation / mixing tank (21) increases. The concentration of the polymer flocculant (P1) added to the functional flocculation / mixing tank (3) is decreased to reduce the concentration rate, and the load on the dehydrator (24) is increased to increase the load of the flocculation / mixing tank (21). The tank pressure is increased to return the sludge amount of the concentrated sludge (Q2) to the set value, and the sludge properties of the raw sludge (Q1) are deteriorated to increase the tank internal pressure of the agglomeration mixing tank (21). When the amount of sludge in the concentrated sludge (Q2) pumped to the tank (21) decreases, the concentration rate is improved by increasing the polymer flocculant (P1) added to the coagulation mixing tank (3) with a concentration function. Reducing the load on the machine (24) and lowering the tank pressure of the coagulation mixing tank (21), Raw sludge supply amount constant control method of the dehydrator according to claim 1, characterized in that to return to the set value sludge of reduced sludge (Q2).   Even if the sludge properties of the raw sludge (Q1) deteriorate and the amount of the polymer flocculant (P1) added to the coagulation / mixing tank with concentration function (3) is increased, the amount of sludge in the concentrated sludge (Q2) remains at a predetermined time. When it does not continuously return to the specified value, the polymer flocculant (P2) is added to the flocculation / mixing tank (21) to improve the filterability, and the flocculated sludge (Q3) supplied to the dehydrator (24) The method for controlling the amount of raw sludge to be supplied to a dehydrator according to claim 4, wherein the amount of sludge is increased and the tank internal pressure of the coagulation mixing tank (21) is reduced to return to a specified value.   In the sludge pre-treatment device provided in the front stage of the dehydrator (24), the fixed-type sludge pump (SP1) and the polymer supply pump (PP1) are connected to the first stage coagulation mixing tank with a concentration function (3), and fixed The raw sludge (Q1) and the polymer flocculant (P1) at a flow rate are supplied to the coagulation mixing tank (3) with a concentration function, and the filtrate (S) is separated from the sludge that has generated flocs to adjust the sludge concentration. At the same time, the concentrated sludge pump (SP2) for extracting the concentrated sludge (Q2) from the agglomeration mixing tank (3) with a concentration function and the polymer supply pump (PP2) are connected to the second stage agglomeration mixing tank (21) for aggregation. The raw sludge of the dehydrator characterized by adjusting the filterability and the extraction amount of the coagulated sludge (Q3) in the mixing tank (21) and maintaining the press-fitting pressure of the coagulated sludge (Q3) to be press-fitted into the dehydrator (24) Supply amount constant control device.   A pressure sensor (PS2) for detecting the tank internal pressure of the second stage flocculation mixing tank (21) and a pressure flow rate for receiving the detection signal of the pressure sensor (PS2) and controlling the rotational speed of the concentrated sludge pump (SP2) The controller (25) is arranged to adjust the sludge flow rate of the concentrated sludge (Q2) to be pumped to the flocculation mixing tank (21) so that the tank internal pressure of the flocculation mixing tank (21) is maintained at a constant level. Sensor (PS1) for detecting the tank internal pressure of the coagulation mixing tank (3) with concentration function, and flow control for increasing / decreasing the rotation speed of the polymer supply pump (PP1) upon receiving the detection signal of the pressure sensor (PS1) And a solid proportional injection controller (27) for receiving a command signal for increasing / decreasing the rotational speed and controlling the rotational speed of the polymer supply pump (PP1), and providing a raw sludge having a constant flow rate. (Q1) coagulation and mixing with concentration function Concentrate as the internal pressure of the coagulation mixing tank with concentration function (3) changes while maintaining the press-fitting pressure of the coagulated sludge (Q3) supplied to (3) and pressed into the dehydrator (24) within the specified value. The tank internal pressure of the coagulation-mixing tank with concentration function (3) is maintained within a specified value by adjusting the chemical injection rate of the polymer coagulant (P1) added to the coagulation-mixing tank with function (3). The raw sludge supply amount constant control apparatus of the dehydrator according to claim 6.   A sludge flow meter (F3) for detecting the sludge flow rate of the concentrated sludge (Q2) and a flow rate controller (28) for receiving a detection signal of the detected sludge flow rate are disposed, and a polymer is provided in the coagulation mixing tank (21). 8. The constant sludge supply amount control device for a dehydrator according to claim 7, wherein a coagulant (P2) is added to improve the coagulation state of the coagulated sludge (Q3) supplied to the dehydrator (24). .